ULEZ has not have improved air quality in London as much as Sadiq Khan has claimed, according to data from local councils.Last year, the Mayor of London credited the £12.50-per-day ultra low emission zone with bringing levels of nitrogen dioxide (NO2) across the capital to within legal limits for the first time.But analysis of official air quality figures from local authorities suggests more than half of all boroughs are still recording illegal levels of the toxic gas, which is largely emitted from diesel vehicles.The NO2 is an annual average of 40 micrograms per cubic metre (ug/m3) of air. Last year, a report from the Department for the Environment, Food, and Rural Affiars (Defra) claimed London fell wholly within this limit for 2024.However, at least 18 areas of the capital are still recording annual average levels above this at individual monitoring stations.One in the centre of Romford recorded an annualised average almost twice the limit in 2024, as did several stations in the City of London - where ULEZ was introduced seven years ago.The findings come after the Mail reported that last year alone, ULEZ generated a record-high income of £219million, compared to £215million in 2024. The charity Asthma + Lung UK, which analysed the figures together with the Healthy Air Coalition, claims that the government is understating the levels of air pollution. Andrew McCracken, from the charity, says that while ULEZ has been 'vital' for reducing pollution people, especially those with lung conditions, deserved full transparency about the air they are breathing. Critics of ULEZ claim its benefit has been overstated after analysis of local air pollution monitors found the air in some parts of London is still above legal limits for nitrogen dioxide